Application of immobilized TiO2 on PVDF dual layer hollow fibre membrane to improve the photocatalytic removal of pharmaceuticals in different water matrices

Abstract

A promising membrane configuration based on immobilized TiO2 on poly(vinylidene fluoride) (PVDF) dual layer hollow fibre membranes was prepared and successfully employed for the photocatalytic degradation of eight pharmaceuticals. Experiments were carried out in a flow reactor of 0.5 L equipped with a lamp emitting at 254 nm, treating groundwater and secondary wastewater effluent. The efficiency of the new catalyst to phototransform target micropollutants was demonstrated, being dependent on the selected compound. Only the application of photocatalysis using the supported catalyst allowed to increase the phototransformation rate of trimethoprim, metoprolol and carbamazepine treating secondary wastewater effluent (1.4–2.2 times faster than photolysis). The determination of electrical energy per order of magnitude of transformation (EEO) confirmed the lowest energy requirements to transform selected pharmaceuticals in secondary effluent employing the supported catalyst (33–58 kW h m−3 compared to 49–79 kW h m−3 applying only photolysis). The detection and identification of transformation products formed during the investigated treatments was performed by UPLC-QTOF/MS/MS. 156 transformation products were detected showing two different types of time profiles, namely a bell-shape trend or a constant increase along reaction time thus accumulating in the reaction mixture. The chemical structure for 19 out of 156 detected compounds was proposed as derived from parent compounds spiked in the secondary effluent.